Cumulative Frequency Curve to automatocally include new data

I'm trying to produce a GEOGERBRA utility for my students to be able to enter their grouped data in the spreadsheet and then be able to see the Ogive (Curve) and for them to be able to see the boxplot...

The problem I'm having is with the SPREADSHEET bit, which I don't really understand:

1) I want the curve to automatically include any extra classes that the students enter in the A-column and B-column (at the moment it doesn't)

2) I want them to be able to see the CUMULATIVE FREQUENCIES in the C-column, when they tick the checkbox (at the moment that doesn't work)

3) I don't really want them to see the remaining D-column and the E-column, but I can't figure out how to hide them

4) I've like the BOX around the three coumns (the 'x', 'freq' and 'CF' columns) to automatically border the data when they introduce extra columns (but if that's not possible, I'd like to know how to re-size the border on a case-by-case basis)

I'd be very grateful for any help you clever boffins can give - I really struggle with this sort of stuff and it always takes me ages, but I am learing slowly and my students are always delighted with the applets that I give them: I've had so much help previously: BIG THANKS IN ADVANCE FOR ANY HELP YOU CAN GIVE...